In the last post we learnt about the GREASE-FALL, which is “how to distribute the fats in order to obtain a specific kind of cream”.
In this post we are going to go a step forward: we will learn about the fatty acids inside the natural fats (oils or butters). This will help you formulate keeping an eye specially to acne problems.
There are many fatty acids in oils and butters.
The most common ones can be divided in this way:
1) Saturated fatty acids:
– palmitic acid
– stearic acid
– lauric acid
2) Monounsaturated fatty acids:
– palmitoleic acid
– oleic acid
3) Polyunsaturated fatty acids:
– linoleic acid (more famous as Omega-6)
– alpha-linolenic acid (more famous as Omega-3)
Saturated fatty acids are found mostly in butters (the high presence of saturated fatty acids, which are fatty acids that like to sit very close next to each other, makes the butters be solid at room temperature! 😉 ) and they determine the density of an oil.
Saturated fatty acids tend to create deposits and this might happen also on the skin. However, if they are in low percentage, there is no problem in the formulation. 🙂
Stearic Acid, as a lone substance, is also used as a thickener in creams and sometimes soaps; its presence however helps the formation of the unfamous white-trail, therefore do not use too much butters which contain this fatty acid in high percentage or there is a higher risk that your cream will make the white-trail on the skin! 🙂 But don’t worry too much: the quality of the cream, however, won’t change 😉
Lauric Acid has been claimed to have antimicrobial properties.
Now to the more interesting (for our skin) Unsaturated fatty acids, if you know a little bit of Chemistry you will already know that the shape of UNsaturated fatty acids makes it difficult for them to sit close close to each other, like the saturated fatty acids. This is why the oils, which contain mostly Unsaturated fatty acids, are liquid at room temperature 🙂
Within the category of Unsaturated fatty acids we find Monounsaturated (therefore Oleic Acid and Palmitoleic Acid) and Polyunsaturated fatty acids (linoleic and alpha-linolenic acids).
The biggest difference in the oils we use in cosmetics is usually the ratio of saturated, monounsaturated and polyunsaturated fatty acids, so most of the times when an oil is marketed as “something special”, well it often isn’t. For example almond, macadamia, hazelnut oils have a very different cost but their fatty acid composition is quite similar. So before you purchase an oil thinking that it will do something magic, take a moment and look up the fatty acid content of the oil, to be sure that it is not too similar to a much cheaper one!
I know it is tempting to think that the oil of the rarest variety of some extremely exotic plant will finally be your skin-changer… but if you have been sticking around this blog enough, you should know by now that I rarely believe in skin-changing ingredients (there are some effective ones, but the slightly different composition of an oil won’t do the trick) 😉 so do always look up the fatty acid content (and then buy the oil anyway, if you really want to, but at least knowing what you are buying!).
Now, to the correlation between fats and acne:
some studies have checked the sebum production of people with and without acne and apparently people who suffer of acne tend to have a higher percentage of monounsaturated fatty acids compared to the polyunsaturated ones.
Applying more monounsaturated fatty acids (specifically the oleic acid) to the skin might create some problem is this case: it tends to increase the percentage of Ca2+ on skin, which leads to higher keratinization. This can cause even more acne problems.
It is worth considering this disparity in the sebum production when we formulate a cream for somebody who suffers of acne.
The idea is to learn about the fatty acid concentration of our oils and butters to be able to add in our “grease fall” ingredients with a higher concentration of polyunsaturated compared to monounsaturated ones.
A practical example: I use very low percentage of butters (0.5-1%, but even this small amount is needed for the consistency of the cream) and then, when I have to pick the oils, I pick them with different densities but I make sure that they are low in Oleic and Palmitoleic Acids, while they are rich in Linoleic and Alpha-Linolenic Acids. This is what I have done and so far and I have had good results 🙂
Online you can very easily find data about even the most exotic oils: both on their density, spreading ability and content of fatty acids.
Here I will just sum up very briefly which oils have relative higher content of linoleic and alpha-linoleic acids:
Black currant oil
Grape seed oil
Passion fruit oil
Sunflower oil – this is the cheapest option
There are also a few butters that, compared to other butters, seem to have a slightly lower content of oleic acid, for example Murumuru butter, Coconut oil and Tucuma butter.
However butters don’t have high content of polyunsaturated fatty acids (or they wouldn’t be butters anymore, as I explained before).
Hope this was helpful! 🙂
I am sure there would be more and more things to tell about fatty acids but maybe in a future post.
Have a great day! 😉